1. Field of the Invention
The structure of this invention resides in the area of outdoor umbrellas and more particularly relates to a patio-type umbrella which has wind-resistant, aerodynamic features.
2. Description of the Prior Art
Patio umbrellas are usually concave, inverted, fabric-covered structures supported by a plurality of struts and ribs mounted on a central mast. Such umbrellas are often adversely affected by strong wind which can blow them over, and many inventions have been directed to improving such patio umbrellas to better withstand strong winds such as by providing vents in their fabric covering and by providing mast structures which can allow wind to pass therethrough in various ways. Some patio umbrellas are spring-loaded, that is, their concave structure is movable when sufficient wind force is exerted thereon. One patio umbrella of the prior art spins on its central shaft when strong wind blows against it in order to dissipate the force of the wind.
Despite the incorporation of such wind-resistant features, prior art canopy umbrellas are still adversely affected by strong wind forces which can turn their canopies inside-out, uproot their masts and/or tip them over. Another negative of prior art structures is that their construction is labor-intensive because of their complicated construction and their many parts. Many times it is completely impractical to repair them because of the high cost of repairing their thin metal struts which can be bent from high winds. Thus, if damaged, such prior art umbrellas must often be thrown away.
Further, the designs of typical prior art umbrellas have been primarily limited to rounded, curved canopies so that they can open symmetrically.